87 - STUDY OF MONONUCLEAR PHAGOCYTES IN VIVO: OVERVIEW

Abstract

This chapter presents an overview of the examination of mononuclear phagocytes in vivo . All who work in vitro acknowledge that tissue culture conditions fall a long way short of reproducing the internal environment, but sometimes there are still surprises. For example, the presence of large amounts of ascorbic acid in the air spaces of the lung might be expected to have some effect on its antimicrobial defenses. The important activities of macrophages include the expression of acquired cellular resistance to infection; the expression of antitumor immunity; and participation in inflammatory reactions leading to tissue destruction. In experiments that can now be regarded as classics, Mackaness and his colleagues showed that activated macrophages are responsible for the expression of acquired cellular resistance to infection and that they become activated under the influence of specifically committed T lymphocytes reacting with antigen. Macrophages are very prominent in inflammatory reactions resulting in tissue damage. One of the most important human diseases in which such reactions occur is rheumatoid arthritis. Based on observations of lesions in man and experimental animals and on biochemical observations on cultured macrophages, strong suggestions have been made that the inflammation and destruction of joint tissue are due in part to the activities of macrophages, notably the release of lysosomal enzymes, neutral proteases, and prostaglandins.